Solutions to pinholes in the coating caused by improper pre-plating treatment
In the electroplating process, the phenomenon of spraying paint on the plating layer often appears bad. This is because the surface has oil stains after electroplating, resulting in poor adhesion. However, when parts are plated, pinholes often occur after plating. Today we will talk about pinholes caused by improper pre-treatment and solutions.
(1) Parts are not degreased or stored improperly during machining. Dust has fallen on the surface and has been left for a long time. Dust and grease are mixed together and it is difficult to remove it, thus forming inconspicuous fine oil spots. Air bubbles stagnate on them to form pinholes.
(2) During polishing of parts, abrasives, polishing pastes, etc. are embedded in the surface micro-pits, which is difficult to clean, and the pits are not deposited on the plating layer, resulting in pin holes.
(3) Incomplete pickling and rust removal of parts or excessive corrosion caused by pickling time, the surface is scattered with carbon enrichment points, and the plating layer can only be deposited around these non-conductive particles during plating to form pinholes.
(1) Adopt a reasonable pre-treatment process to ensure the quality of pre-treatment. The pre-treatment process is as follows: parts hanging → chemical degreasing → hot water washing → flowing water washing → pickling and rust removal → two flowing water washing → electric degreasing → Hot water washing → Flowing water washing → Weak corrosion → Twice flowing water washing, strictly implement the process operating procedures, and strengthen the maintenance and management of the bath fluid.
(2) The surface of the parts is not clean before plating, and there are oil dirt particles and other non-conductive particles. It can be washed with a brush moistened with alkaline water, and then degreased by electricity. Small parts are best polished.
(3) When oil layer appears on the liquid surface of chemical degreasing or electrochemical degreasing tank, it should be salvaged in time. Pay attention to the complete removal of polishing paste on the parts after grinding and polishing.
(4) Be sure to control the pickling time. Once the rust is removed, it should be removed and cleaned immediately. To prevent over-corrosion of parts, a certain amount of corrosion inhibitor should be added to the pickling solution.